@Will I also have a tutorial in Yoshi's house, to show how those blocks work, and reacquaint them with the old blocks. I do understand where you're coming from, but most kill blocks I meet, are red/black. I have more kill blocks than munchers too, just to mention..
@Laularu Green block is like the ugly block. Not a replacement, but one that just looks better in time of need.
It turns into the next map16, so you could use it to look like SMB2 Doors also.
Level two: after the optional switch palace, of course.
This part is more of the "Kaizo part of this hack" Although it is rather easy.. (Not so easy if you choose not to get the switch.)